# Right Triangle Trigonometry: Intro

- Author:
- Nicola Trubridge, Tim Brzezinski

- Topic:
- Cosine, Ratios, Right Triangles, Similar Triangles, Sine, Triangles, Trigonometry

**Key Question:**Hopefully, you noticed that when you keep the blue angle fixed and move only the white vertices, the value of each ratio never changes (even though the side lengths do)!

*Why does this occur?*Explain!